Could US Congress stop Trump from taking over Greenland?

President Donald Trump’s push to acquire Greenland has sparked a backlash from Republicans in Congress, as lawmakers voice growing concern about US military interventions overseas.

But it remains unclear if enough Republicans are willing to join Democrats to block a takeover of the island territory – and whether Trump would bow to pressure from Congress, or act alone as he’s done several times in a second term marked by growing American entanglements abroad.

The focus on Greenland has grown into a broader discussion over the Trump administration’s unilateral use of military force, along with diplomatic and economic coercion, to project power in Venezuela, Iran and elsewhere around the world.

Republicans have largely backed Trump’s foreign policy agenda since he returned to the White House. But now, a growing number are siding with Democrats in Congress and Nato allies who say a takeover of Greenland would violate US and international law.

In recent days, some Republican leaders have said there’s little interest in the US buying Greenland or seizing it through military force. Some Republican lawmakers have also joined Democrats in opposing a new plan by Trump to place tariffs on countries that don’t back his bid to acquire the territory, which is self-governed but controlled by Denmark.

The proposed tariffs would be “bad for America, bad for American businesses, and bad for America’s allies,” Senator Thom Tillis of North Carolina wrote on social media, adding that the move would benefit China and Russia. “It’s great for Putin, Xi and other adversaries who want to see Nato divided.”

Other Republicans said Trump’s ambition to annex Greenland was threatening to undermine the Nato alliance – to which both the US and Denmark belong – in a moment of growing tension between the US and European allies.

“Respect for the sovereignty of the people of Greenland should be non-negotiable,” Senator Lisa Murkowski, the co-chair of the Senate Arctic Caucus, said in a statement.

Trump has argued the US must own the territory to better compete with China and Russia in the Arctic, and has vowed to take it “one way or another”.

On Tuesday, the US president downplayed concerns that the issue was hurting Nato when asked by the BBC if he was willing to see the decades-old security alliance collapse as a consequence of his push for the territory. Trump reiterated his view that ownership of Greenland was critical for US and global security.

“We need [Greenland] for national security and even world security,” he said.

But Trump’s insistence on obtaining the territory is increasingly unpopular on Capitol Hill.

Congress has some options to try to reign Trump in, if Republicans and Democrats do choose to pick a fight with the president over Greenland.

Congress has the power of the purse and in theory would have to approve funding used to buy Greenland, experts said. Denmark and Greenland have both insisted the island isn’t for sale.

“If Trump wants to buy Greenland it would require an act of Congress to provide the funds to do so,” said Daniel Schuman, the executive director of the American Governance Institute and an expert on congressional procedure. It’s unlikely that Congress could repurpose existing funding to buy the territory, Schuman added.

Still, the administration has expanded the use of executive power to enact Trump’s immigration and tariff agenda, among other issues. The administration might try to claim some new authority to seize Greenland that would allow it to overrule any roadblocks by Congress, Schuman said.

Lawmakers worried about a military incursion in Greenland have signalled support for measures prohibiting any US action without congressional approval. But it’s unclear if the proposals have enough Republican support to pass in either chamber of Congress.

Five Senate Republicans joined Democrats earlier this month to advance a bill that would have blocked the administration from taking further military action in Venezuela, following the attack in December that deposed former President Nicolás Maduro.

The Venezuela war powers resolution ultimately failed to get through the Senate. But it signalled mounting frustration from Republican and Democratic lawmakers with Trump’s use of military force abroad, after he ran in 2024 on a promise to reduce US involvement in foreign conflicts. Last week a bipartisan congressional delegation visited Denmark in a symbolic show of support for Greenland.

It’s also unclear how the Senate, which ratifies treaties, would respond if the US reached some sort of agreement with Denmark to take over part or all of Greenland.

The US has an existing arrangement with Denmark established in 1951 that allows the US to expand its military presence in Greenland. Murkowski and other Republicans have argued that the US doesn’t need to take over the territory to address national security needs in the region.

The Senate could try to thwart Trump by opposing a treaty between the US and Denmark, in the event the two nations reach an agreement. Treaties require two-thirds support in the Senate for ratification, which Republicans currently fall well short of.

Some Republicans have already indicated that they’d consider breaking with Trump over Greenland. Senator Mitch McConnell of Kentucky, the former majority leader in the upper chamber of Congress, told reporters that a US takeover of the territory would “shatter the trust of allies”.

Faced with growing Republican concern over Greenland, Trump could look to strike a deal that falls short of a formal treaty and doesn’t require Senate approval. But it’s unclear if presidents have the authority to make such agreements without input from Congress, analysts said.

“Plenty of international agreements are concluded in forms other than treaties,” said Josh Chafetz, a professor at Georgetown Law, but “I’m sceptical that something of this magnitude could be concluded as a pure executive agreement.”

Trump did not say on Tuesday whether he believed he was constrained by anything in his pursuit of Greenland. Asked how far he was willing to go, Trump told reporters to stay tuned.

“I think something is going to happen that’s going to be very good for everybody,” Trump said.

Additional reporting by Kayla Epstein